Field of the Invention and Related Art Statement
This invention generally relates to a technique for setting operational conditions of an apparatus for recording and/or reproducing information on and/or from a record medium by using a pick-up, and more particularly relates to an information recording and/or reproducing apparatus having a faculty for automatically setting operational conditions in an easy and prompt manner.
There have been proposed various kinds of apparatuses of the kind mentioned above. For instance, information writing and reading apparatuses using magnetic disk, optical disk, optical card and magnetooptical magnetic disk as the record medium have been proposed. Such an apparatus is generally composed of a main unit and a pick-up unit In general, the pick-up unit is manufactured separately from the main unit and a pick-up unit and a main unit are assembled to construct an information recording and/or reproducing apparatus. When the pick-up unit in the apparatus becomes out of order, the pick-up unit is detached from the main unit and is replaced by a new one. Since respective pick-up units are not formed completely identical with each other and there are always differences between particular pick-up units mainly due to a possible tolerance in manufacture. In order to compensate these differences, there is provided mechanical and/or electrical adjusting means in the main unit. For example, in a signal processing circuit of the main unit, there is provided a variable resistor which is adjusted when the pick-up unit is replaced by a new one such that the operational conditions of the signal processing circuit are adopted to operational characteristics of the new pick-up unit.
However, since the variable resistor is provided in the main unit, every time the pick-up unit is replaced, it is necessary to access the variable resistor and adjust it in accordance with the operational characteristics of the pick-up unit. This is apparently cumbersome and requires a time consuming labor work of an expert.
In order to avoid such a drawback, in copending U.S. Patent application Ser. No. 07/657,507 filed on Feb. 19, 1991 there is proposed to provide a memory in a pick-up unit and to store characteristic data for setting the various operational conditions specific to the relevant pick-up unit. When such a pick-up unit is assembled with a main unit, the characteristic data is read out of the memory and the operational conditions of the main unit are automatically adjusted in accordance with the read out characteristic data. Therefore, when the pick-up unit is replaced by a new one, it is no more necessary to adjust manually the adjusting means such as the variable resistor provided in the main unit.
For instance, in a system using the optical cards as the record medium, it is sometimes required to change the optical cards and to introduce new optical cards. Usually the new optical cards have different light reflectance and recording sensitivity than the currently used optical cards. Therefore, when the optical cards are changed, it is necessary to change various operational conditions such as a threshold level for converting a signal read out of the optical card into a bivalent signal, a reading laser output power for reading information out of the optical card, a writing laser output power for writing information on the optical card, and a writing pulse width. In such a case, even if the pick-up unit having the memory installed therein is used, the correct operation could not be attained unless the characteristic data stored in the memory is rewritten in accordance with the characteristics of the new optical cards. However, the contents in the memory could not be rewritten in an easy and prompt manner, because it is necessary to remove the pick-up unit from the main unit in order to access the memory.